bonding: fix l23 and l34 load balancing in forwarding path

Since commit 6b923cb7188d46 (bonding: support for IPv6 transmit hashing)
bonding doesn't properly hash traffic in forwarding setups.

Vitaly V. Bursov diagnosed that skb_network_header_len() returned 0 in
this case.

More generally, the transport header might not be in the skb head.

Use pskb_may_pull() & skb_header_pointer() to get it right, and use
proto_ports_offset() in bond_xmit_hash_policy_l34() to get support for
more protocols than TCP and UDP.

Reported-by: Vitaly V. Bursov <vitalyb@telenet.dn.ua>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: John Eaglesham <linux@8192.net>
Tested-by: Vitaly V. Bursov <vitalyb@telenet.dn.ua>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 30 insertions, 25 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index a61a760484f7..dea8ce20fea4 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3296,20 +3296,22 @@ static int bond_xmit_hash_policy_l2(struct sk_buff *skb, int count)
  */
 static int bond_xmit_hash_policy_l23(struct sk_buff *skb, int count)
 {
-        struct ethhdr *data = (struct ethhdr *)skb->data;
-        struct iphdr *iph;
-        struct ipv6hdr *ipv6h;
+        const struct ethhdr *data;
+        const struct iphdr *iph;
+        const struct ipv6hdr *ipv6h;
         u32 v6hash;
-        __be32 *s, *d;
+        const __be32 *s, *d;
 
         if (skb->protocol == htons(ETH_P_IP) &&
-            skb_network_header_len(skb) >= sizeof(*iph)) {
+            pskb_network_may_pull(skb, sizeof(*iph))) {
                 iph = ip_hdr(skb);
+                data = (struct ethhdr *)skb->data;
                 return ((ntohl(iph->saddr ^ iph->daddr) & 0xffff) ^
                         (data->h_dest[5] ^ data->h_source[5])) % count;
         } else if (skb->protocol == htons(ETH_P_IPV6) &&
-                   skb_network_header_len(skb) >= sizeof(*ipv6h)) {
+                   pskb_network_may_pull(skb, sizeof(*ipv6h))) {
                 ipv6h = ipv6_hdr(skb);
+                data = (struct ethhdr *)skb->data;
                 s = &ipv6h->saddr.s6_addr32[0];
                 d = &ipv6h->daddr.s6_addr32[0];
                 v6hash = (s[1] ^ d[1]) ^ (s[2] ^ d[2]) ^ (s[3] ^ d[3]);
@@ -3328,33 +3330,36 @@ static int bond_xmit_hash_policy_l23(struct sk_buff *skb, int count)
 static int bond_xmit_hash_policy_l34(struct sk_buff *skb, int count)
 {
         u32 layer4_xor = 0;
-        struct iphdr *iph;
-        struct ipv6hdr *ipv6h;
-        __be32 *s, *d;
-        __be16 *layer4hdr;
+        const struct iphdr *iph;
+        const struct ipv6hdr *ipv6h;
+        const __be32 *s, *d;
+        const __be16 *l4 = NULL;
+        __be16 _l4[2];
+        int noff = skb_network_offset(skb);
+        int poff;
 
         if (skb->protocol == htons(ETH_P_IP) &&
-            skb_network_header_len(skb) >= sizeof(*iph)) {
+            pskb_may_pull(skb, noff + sizeof(*iph))) {
                 iph = ip_hdr(skb);
-                if (!ip_is_fragment(iph) &&
-                    (iph->protocol == IPPROTO_TCP ||
-                     iph->protocol == IPPROTO_UDP) &&
-                    (skb_headlen(skb) - skb_network_offset(skb) >=
-                     iph->ihl * sizeof(u32) + sizeof(*layer4hdr) * 2)) {
-                        layer4hdr = (__be16 *)((u32 *)iph + iph->ihl);
-                        layer4_xor = ntohs(*layer4hdr ^ *(layer4hdr + 1));
+                poff = proto_ports_offset(iph->protocol);
+
+                if (!ip_is_fragment(iph) && poff >= 0) {
+                        l4 = skb_header_pointer(skb, noff + (iph->ihl << 2) + poff,
+                                                sizeof(_l4), &_l4);
+                        if (l4)
+                                layer4_xor = ntohs(l4[0] ^ l4[1]);
                 }
                 return (layer4_xor ^
                         ((ntohl(iph->saddr ^ iph->daddr)) & 0xffff)) % count;
         } else if (skb->protocol == htons(ETH_P_IPV6) &&
-                   skb_network_header_len(skb) >= sizeof(*ipv6h)) {
+                   pskb_may_pull(skb, noff + sizeof(*ipv6h))) {
                 ipv6h = ipv6_hdr(skb);
-                if ((ipv6h->nexthdr == IPPROTO_TCP ||
-                     ipv6h->nexthdr == IPPROTO_UDP) &&
-                    (skb_headlen(skb) - skb_network_offset(skb) >=
-                     sizeof(*ipv6h) + sizeof(*layer4hdr) * 2)) {
-                        layer4hdr = (__be16 *)(ipv6h + 1);
-                        layer4_xor = ntohs(*layer4hdr ^ *(layer4hdr + 1));
+                poff = proto_ports_offset(ipv6h->nexthdr);
+                if (poff >= 0) {
+                        l4 = skb_header_pointer(skb, noff + sizeof(*ipv6h) + poff,
+                                                sizeof(_l4), &_l4);
+                        if (l4)
+                                layer4_xor = ntohs(l4[0] ^ l4[1]);
                 }
                 s = &ipv6h->saddr.s6_addr32[0];
                 d = &ipv6h->daddr.s6_addr32[0];